Composite structure and high speed bobbin

ABSTRACT

A composite structure of alternating sheets of glass cloth and organic paper or cloth both impregnated with an organic resin is disclosed. A high speed bobbin is also disclosed where a cylinder of the composite structure has an outer coating or organic fiber reinforced resin. Preferably, the bobbin has a four-layered structure. The outside external layer is organic paper or cloth reinforced resin and the inside external layer is phenolic resin impregnated paper or cloth. The two internal layers are the composite structure and phenolic resin impregnated paper or cloth.

flnited States Patent [191 Crawford et a1.

COMPOSITE STRUCTURE AND HIGH SPEED BOBBIN Inventors: Thomas G. Crawford, Hampton;

William E. Kearse, Fairfax, both of SC.

Westinghouse Electric Corporation, Pittsburgh, Pa.

Filed: June 6, 1972 Appl. N0.: 260,090

Assignee:

11.5. C1 242/l18.32, 138/DIG. 2, 138/141, 161/84,161/93 lnt. Cl. B6511 75/10 Field of Search 242/ll8.32, 118.31, 118.3, 242/118, 118.7; 138/D1G. 2, 144, 125, 141; 161/84, 85, 88, 89, 93, DIG. 4, DIG. 2

References Cited UNITED STATES PATENTS Slayter 138/D1G. 2

[ Mar. 18, 1975 2,854,031 9/1958 Donaldson 138/144 2,877,150 3/1959 Wilson 1. 138/144 X 2,945,638 7/1960 Crawford et a1 242/1 18.32 3,054,428 9/1962 Crawford 242/118.32 X 3,553,046 1/1971 Crawford et a1 242/1 18.32

Primary Examiner-George F. Mautz Attorney, Agent, or Firm-R. D. Fuerle [57] ABSTRACT A composite structure of alternating sheets of glass cloth and organic paper or cloth both impregnated with an organic resin is disclosed. A high speed bobbin is also disclosed where a cylinder of the composite structure has an outer coating or organic fiber reinforced resin. Preferably, the bobbin has a four-layered structure. The outside external layer is organic paper or cloth reinforced resin and the inside external layer is phenolic resin impregnated paper or cloth. The two internal layers are the composite structure and phenolic resin impregnated paper or cloth.

15 Claims, 2 Drawing Figures COMPOSITE STRUCTURE AND HIGH SPEED BOBIBIN BACKGROUND OF THE INVENTION In the textile industry as yarn is made it is wound onto bobbins for later use in weaving fabrics. The yarn is guided across the bobbin and is compressed onto the bobbin by a steel traverse drive roll. The roll rides against the bobbin surface initially until a layer of yarn has been wound onto the bobbin.

Prior art bobbins were made of paper impregnated with phenol-formaldehyde resin and, until recently, these bobbins functioned satisfactorily (see U.S. Pat. Nos. 3,054,428, 3,436,034, and 2,879,010).

However, the recent great increase in the demand for double-knit clothes has caused textile manufacturers to increase the speed of many of their operations, winding speed being increased from about 4000-6000 rpm to about 12,000 rpm. When yarn is wound onto a phenolformaldehyde paper bobbin at these high speeds the steel roll abrades the bobbin creating a brown dust which infests the yarn and must be removed by an additional operation. Also, the double-knit yarn is crimped and wound in a heated, stretched, or uncrimped condition which results in a compressive force on the bobbin of about 1500 psi., a force which collapses prior art bobbins.

When only part of the yarn on a bobbin is used the remaining yarn is simply forced axially off the bobbin so that the bobbin can be reused. This operation exerts about 6000 lbs. of pressure on the bobbin which prior art bobbins could not withstand.

Bobbins containing glass reinforced resin (see U.S. Pat. Nos. 2,945,638 and 3,350,030) have been tried but did not stand up well under the stresses imposed on them.

SUMMARY OF THE INVENTION.

We have found that a composite structure of alternating sheets of glass cloth and organic paper or cloth impregnated and bonded together with an organic resin is an exceptionally strong and useful material for high speed bobbins and other applications. We postulate that the sheets of organic paper or cloth prevent the sheets of glass cloth from rubbing together as the structure flexes, which would otherwise abrade the glass and deteriorate the structure.

The preferred bobbins of this invention deflect less than 0.017 inches under an external force of 1500 psi., a severe test of the forces produced by double-knit yarn. They can also easily withstand the 6000 lbs. of axially applied pressure required to remove scrap yarn from the bobbin.

In addition, we have found that the brown dust previously encountered can be eliminated if the bobbin has an outside external surface of a paper of cloth impregnated with a white epoxy or melamine resin. This outside external surface can be inexpensively resurfaced if necessary.

DESCRIPTION OF THE INVENTION FIG. I is an isometric sectional view of a composite structure according to this invention.

FIG. 2 is an isometric view ofa certain presently preferred embodiment ofa bobbin according to this invention being wound with yarn.

In FIG. 1, composite structure 1 is made up of sheets of glass cloth 2 alternating with sheets of organic cloth or paper-'3, both impregnated with a cured organic resin 4.

In FIG. 2, a preferred bobbin 5 is made up of four layers, an outside external layer 6 of organic paper or cloth impregnated with resin, an inside external layer 7 of organic paper or cloth impregnated with a phenolic resin, an internal layer 8 of the composite structure where the alternating sheets are concentric, and a second internal layer 9 of organic paper or cloth impregnated with a phenolic resin. The bobbin rides over shaft 10. A steel traverse drive roll 11 on shaft 12 guides yarn 13 across the bobbin and compresses it against the bobbin.

The composite structure may be in the form of a plate having flat alternating sheets or of a rod or tube having concentric alternating sheets. The type of resin used, the percentage of resin, and thickness of each sheet will depend upon the purpose for which the composite structure is to be used. For bobbins and most other structures the glass cloth in the composite structure is preferably about 3 to about 20 mils thick as this range provides adequate strength and flexibility. For maximum strength, the glass cloth is preferably woven directional glass cloth where the ratio of fiber tensile strength in the warp direction to the fill direction is about 5 to 1 to about 12 to I. (The warp direction is perpendicular to the axis of the bobbin.) Nonwoven (i.e., matted) cloth could be used but it is not preferred as it is not as strong as woven cloth. The organic paper or cloth is preferably about 3 to 6 mils thick as this range is usually adequate to prevent the glass sheets from abrading themselves. The composite structure in a bobbin preferably has about 8 to about 32 sheets of glass cloth alternating with the same number of sheets of organic paper or cloth.

The organic paper or cloth should preferably be inexpensive and have a high rigidity in order to support the glass cloth. While almost any organic (i.e., noninorganic) paper or cloth could be used, including bleached kraft paper, bleached alpha paper, rag-stock paper, cotton linters, cotton cloth, etc., it is preferred to use natural kraft paper as it is strong and has good impact resistance. Preferably about 30 to about 45% (all percentages herein are by weight) of the composite structure is resin and about 55 to about is glass and paper or cloth. The resin is preferably a phenolic resin such as phenol-formaldehyde, cresylic acid formaldehyde, melamine-formaldehyde, or mixtures thereof, as these resins are inexpensive and work well. Of the particular resins listed, phenol-formaldehyde is the most suitable and least expensive.

While the composite structure in the bobbin gives it strength, the second internal layer is less expensive and it is used as fill when a thicker layer of composite structure is not needed for strength. This layer is preferably about 3 to about 6 mils thick and consists of about 45 to about 65% phenolic resin as hereinbefore described and about 35 to about 55% organic paper or cloth as hereinbefore described.

The two internal layers are preferably in the order shown in FIG. 2, as that order is stronger, but they could also be reversed. If they are reversed then the internal paper or cloth layer merges with the inside external layer. The inside external layer is preferably about 6 to about 60 mils thick and may be of the same composition as the internal paper or cloth layer. The purpose of the inside external layer is to prevent the glass in the composite structure from attacking the steel shaft over which the bobbin rides.

The outside external layer protects the steel traverse drive roll from the glass in the composite layer and is typically about 1/32 to about /8 inch thick. The outside external layer of the preferred bobbin is about 20 to about 35% organic material impregnated with about-65 to about 80% thermosetting organic resin. The organic material is preferably cloth, preferably woven, as it is more durable, but it could also be a paper or an unwoven cloth. The organic material is preferably about 0.010 to about 0.030 inches thick. The organic material may be polyethylene terephthalate, cotton, polyester, nylon, etc., but polyethylene terephthalate is preferred as it has better wear resistance. Examples of thermosetting organic resins include epoxy, melamineformaldehyde, acrylic, polyester, etc. Preferably the resin is white to avoid staining the yarn. Epoxy or melamine resins are preferred as they are the strongest. Phenol-formaldehyde is preferably not used as it tends to discolor the yarn.

The composite structure, if in a plate form, can be made by stacking alternating sheets of resinimpregnated glass cloth and paper or cloth, pressing and curing. If it is in a cylindrical form, a sheet of paper or cloth and glass cloth are passed together through a resin bath, scraped to remove excess resin, partially cured and wound over a mandrel. Rolls heat and compress the sheets on the mandrel. The cylinder is then cured, removed from the mandrel and machined to the dimensions desired. The preferred bobbin is made in a similar manner, except that the appropriate materials and resins are used for the different layers. The resins should be selected so that they are compatible (i.e., adhereto each other) and cure at about the same temperature so that the bobbin can be cured in a single operation. A typical bobbin is about 3 to about 6 inches l.D., about A to about 4 inches thick, and about 5 to about 17 inches long. I

The following example further illustrates this invention.

EXAMPLE A 6 mil thick unbleached natural kraft paper 50 inches wide, air resistance seconds /100 cc maximum 7 minimum 4, Mullen burst strength 35 lbs. min., basic weight 24 X 36-500 maximum 54 minimum 49, weight 6 inches square maximum 2.05 grams, minimum 1.85 grams, was impregnated with 99.65% varnish and 0.35% wetting agent to a resin ratio of 2.20 to 2.35 and a greenness or flow of 12 to 20%.

The composition of the varnish was: 33.0% phenol, 9.2% styrene, 2.0% tung oil, 0.13% phenol-sulfonic acid, 29.0% formaldehyde, 0.16% lime, 0.13% ethylene-diamine, 0.22% ammonium hydroxide, 12.00% toluene, and 14.16% methanol.

Theimpregnated kraft paper was passed over a hot roll (140 to 160C) at 20 to 40 inches per minute and was wound on a 3-11/16 inch diameter hot mandrel (90 to 110C) until it was three wraps thick.

The operation was stopped and a directional glass cloth (warp-to-fill ratio 49 to 30) 50 inches wide and 0.011 inches thick was impregnated with resin of the following composition to a glass-to-resin ratio of 1.53 to 1.58 and a greenness of 7 to 14%: 57% phenolformaldehyde varnish, 43% diepoxide of about diglycidyl ether of bisphenol A and about 15% oligomers of bisphenol A and epichlorohydrin (E.E.W. 180 to 195, viscosity 10,000 to 16,000 cps), sold by Shell Chemical Company under the trademark Epon 828.

The phenol-formaldehyde varnish had the following composition: 38.4% phenol, 36.2% stabilized formaldehyde, 1.0% ammonia, 12.2% methanol, and 12.2% toluene. The resinimpregnated glass cloth was placed over the kraft paper and wrapped onto the mandrel with it. When the composite layer was 4; inches thick the operation was stopped, the glass cut, and the operation continued with only the kraft paper. When the kraft paper was 3/16 inches thick on the mandrel, the operation was stopped and the kraft paper cut.

A scoured, desized, and heat-set polyester terephthalate (Dacron) woven cloth having a 1% maximum extractable content weight of 4.1 ounces/sq. yd., thread count/in. of warp 44, till 44, and average tensile strength ofwarp 123 lbs./in. fill 129 lbs./in. was impreg' nated with the following resin to a resin ratio of 2.80-3.00 and greenness or flow of l030%: 20.5 Epon 828 diepoxide /25.3% diglycidyl ether of bisphenol A at 80% solids in acetone (E.E.W. 450 to 550, viscosity 1290 to 6340), sold by Shell Chemical Company under the trademark Epon lA-80, 30.7% chlorendix anhydride 23.5% toluene.

The resin-impregnated Dacron cloth was wrapped over the mandrel to a thickness of 3/32 inches and the tube was heated for 5 hours at C. The tube was cooled, removed from the mandrel, and a 9% inch section was sawed off and machined to 9 /8 inches long and 0.400 inches thick.

Under an external hydraulic pressure of 1500 lbs./in. the bobbin deflected inward less than 0.017 inches and returned to its original dimensions within 0.001 inches after the pressure was released. It also withstood a 6000 lbs. lateral pressure without breaking or cracking. The bobbin was tested in a double-knit yarn factory and performed very well, did not leave dust on the yarn, and was reused many times.

We claim as our invention:

1. A composite structure comprising at least four sheets of glass cloth, each sheet separated from adjacent sheets by at least one sheet of a material selected from the group consisting of organic paper and cloth, said sheets being impregnated and bonded together with a cured organic resin.

2. A composite structure according to claim 1 wherein said sheets are concentric and form a cylinder.

3. A bobbin comprising a composite structure according to claim 2 having an outside external layer of organic fiber impregnated with a cured thermosetting resin.

4. A bobbin according to claim 3 wherein said cured thermosetting resin is a white resin selected from the group consisting of epoxy resins and melamine resins.

5. A bobbin according to claim 3 which has an inside external layer of a material selected from the group consisting of paper and cloth impregnated with a phenolic resin.

6. A bobbin comprising a cylinder having four layers, the outside external layer of said cylinder being about 1/32 to about /8 inch thick and comprising an organic material selected from the group consisting of paper and cloth impregnated with a cured thermosetting resin, the inside external layer being about 6 to about 60 mils thick and comprising an organic material selected from the group consisting of paper and cloth impregnated with a cured phenolic resin, one of the two internal layers (A) being about 3 to about 6 mils thick and comprising an organic material selected from the group consisting of paper and cloth impregnated with a cured phenolic resin, and the other internal layer (B) being a composite structure which comprises about 8 to about 32 sheets of glass cloth, each sheet separated from adjacent sheets by at least one sheet of an organic material selected from the group consisting of paper and cloth, said sheets being impregnated and bonded together with a cured phenolic resin.

7. A bobbin according to claim 6 wherein said phenolic resin in said composite structure is about 30 to about 45% of said composite structure and is selected from the group consisting of phenolic formaldehyde resins, cresylic acid formaldehyde resins, melamineformaldehyde resins, and mixtures thereof.

8. A bobbin according to claim 6 wherein said outside external layer comprises about to about 35% polyethylene terephthalate woven cloth and about 65 to about 80% selected from the group consisting of epoxy resin and melamine resin.

9. A bobbin according to claim 6 wherein said paper is natural kraft paper.

10. A bobbin according to claim 6 wherein said layer (A) comprises about 45 to about 65% of a resin selected from the group consisting of phenolic formaldehyde resins, cresylic acid formaldehyde resins, melamine-formaldehyde resins and mixtures thereof, and about 35 to about 55% of an organic material selected from the group consisting of cloth and paper.

11. A bobbin according to claim 6 wherein said inside external layer comprises about 45 to about 65% of a phenolic resin selected from the group consisting of phenol formaldehyde resins, cresylic acid formaldehyde resins, and mixtures thereof.

12. A bobbin according to claim 6 wherein said cylinder is about 5 to about 17 inches long, about 3 to about 6 inches inside diameter, and about A to about /1 inches thick.

13. A bobbin according to claim 6 wherein layer (B) is inside layer (A).

14. A bobbin according to claim 6 wherein the glass cloth in said composite structure is about 3 to about 20 mils thick, said glass cloth is directional glass cloth having a ratio of fiber tensile strength in the warp direction to the fill direction of about 5 to 1 to about l2 to l, and said organic material in said composite structure is about 3 to 6 mils thick.

15. A bobbin according to claim. 7 wherein said phenolic resin is phenol-formaldehyde. 

1. A composite structure comprising at least four sheets of glass cloth, each sheet separated from adjacent sheets by at least one sheet of a material selected from the group consisting of organic paper and cloth, said sheets being impregnated and bonded together with a cured organic resin.
 2. A composite structure according to claim 1 wherein said sheets are concentric and form a cylinder.
 3. A bobbin comprising a composite structure according to claim 2 having an outside external layer of organic fiber impregnated with a cured thermosetting resin.
 4. A bobbin according to claim 3 wherein said cured thermosetting resin is a white resin selected from the group consisting of epoxy resins and melamine resins.
 5. A bobbin according to claim 3 which has an inside external layer of a material selected from the group consisting of paper and cloth impregnated with a phenolic resin.
 6. A BOBBIN COMPRISING A CYLINDER HAVING FOUR LAYERS, THE OUTSIDE EXTERNAL LAYER OF SAID CYLINDER BEING ABOUT 1/32 TO ABOUT 1/8 INCH THICK AND COMPRISING AN ORGANIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF PAPER AND CLOTH INPREGNATED WITH A CURED THERMOSETTING RESIN, THE INSIDE EXTERNAL LAYER BEING ABOUT 6 TO ABOUT 60 MILS THICK AND COMPRISING AN ORGAIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF PAPER AND CLOTH IMPREGNATED WITH A CURED PHENOLIC RESIN, ONE OF THE TWO INTERNAL LAYERS (A) BEING ABOUT 3 TO ABOUT 6 MILS THICK AND COMPRISING AN ORGAIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF PAPER AND CLOTH IMPREGNATED WITH A CURED PHENOLIC RESIN, AND THE OTHER INTERNAL LAYER (B) BEING A COMPOSITE STRUCTURE WHICH COMPRISES ABOUT 8 TO ABOUT 32 SHEETS OF GLASS CLOTH, EACH SHEET SEPARATED FROM ADJACENT SHEETS FROM THE GROUP ONE SHEET OF AN ORGANIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF PAPER AND CLOTH, SAID SHEETS BEING INPREGNATED AND BONDED TOGETHER WITH A CURED PHENOLIC RESIN.
 7. A bobbin according to claim 6 wherein said phenolic resin in said composite structure is about 30 to about 45% of said composite structure and is selected from the group consisting of phenolic formaldehyde resins, cresylic acid formaldehyde resins, melamine-formaldehyde resins, and mixtures thereof.
 8. A bobbin according to claim 6 wherein said outside external layer comprises about 20 to about 35% polyethylene terephthalate woven cloth and about 65 to about 80% selected from the group consisting of epoxy resin and melamine resin.
 9. A bobbin according to claim 6 wherein said paper is natural kraft paper.
 10. A bobbin according to claim 6 wherein said layer (A) comprises about 45 to about 65% of a resin selected from the group consisting of phenolic formaldehyde resins, cresylic acid formaldehyde resins, melamine-formaldehyde resins and mixtures thereof, and about 35 to about 55% of an organic material selected from the group consisting of cloth and paper.
 11. A bobbin according to claim 6 wherein said inside external layer comprises about 45 to about 65% of a phenolic resin selected from the group consisting of phenol formaldehyde resins, cresylic acid formaldehyde resins, and mixtures thereof.
 12. A bobbin according to claim 6 wherein said cylinder is about 5 to about 17 inches long, about 3 to about 6 inches inside diameter, and about 1/4 to about 3/4 inches thick.
 13. A bobbin according to claim 6 wherein layer (B) is inside layer (A).
 14. A bobbin according to claim 6 wherein the glass cloth in said composite structure is about 3 to about 20 mils thick, said glass cloth is directional glass cloth having a ratio of fiber tensile strength in the warp direction to the fill direction of about 5 to 1 to about 12 to 1, and said organic material in said composite structure is about 3 to 6 mils thick.
 15. A bobbin according to claim 7 wherein said phenolic resin is phenol-formaldehyde. 